The reduction in the number and frequency of insecticide applications in transgenic crops has favored population outbreaks of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in various Bt (Bacillus thuringiensis Berliner) soybean cultivars [Glycine max (L.) Merrill; Fabaceae], reflecting the fact that plants have different levels of attractiveness to insects. The identification of Bt soybean cultivars resistant to whitefly represents a viable and effective control alternative. The objective of this study was to characterize the vertical distribution of insects on the plant and to identify Bt soybean cultivars less attractive to B. tabaci. The insects used were collected in tomato crops, and the whitefly population was maintained on leaf cabbage plants. Fifteen soybean cultivars were evaluated to determine attractiveness to whitefly. Soybean plants were stratified into upper, middle, and lower thirds. Multiple-choice and no-choice bioassays were carried out with the 15 cultivars. Subsequently, 10 cultivars were selected for a new multiple-choice assay. The parameters evaluated were the number of adults per leaflet and number of eggs cm⁻²; the degree of colonization by nymphs was determined only in the multiple-choice assay. The density and length of trichomes of the 15 cultivars were also characterized. It was shown that the upper third of the plant was the most attractive, having the largest number of adults and colonizing nymphs. The cultivars BRS 9280RR, M 8808, and M 8644IPRO showed low levels of B. tabaci infestation by adults, eggs, and nymphs in the bioassays performed. There was a negative correlation between trichome length and density with the number of adults, eggs, and degree of colonization by nymphs. The vertical distribution and attractiveness of soybean cultivars to whitefly are discussed.

中文翻译：

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烟粉虱在大豆上的垂直分布及品种吸引力

转基因作物中杀虫剂施用次数和频率的减少有利于烟粉虱（Gennadius）（半翅目：粉虱科）在各种 Bt（苏云金芽孢杆菌）大豆品种 [ Glycine max (L.) Merrill; Fabaceae]，反映了植物对昆虫的吸引力程度不同的事实。鉴定出抗粉虱的 Bt 大豆品种代表了一种可行且有效的控制替代方案。本研究的目的是表征昆虫在植物上的垂直分布，并确定对烟粉虱不太有吸引力的 Bt 大豆品种. 使用的昆虫是在番茄作物中收集的，粉虱种群在叶甘蓝植株上维持。评估了 15 个大豆品种以确定对粉虱的吸引力。大豆植物分为上、中和下三分之一。对 15 个品种进行了多项选择和非选择生物测定。随后，选择了 10 个栽培品种进行新的多项选择试验。评估的参数是每张传单的成虫数和卵数 cm ^-2; 若虫的定殖程度仅在多项选择试验中确定。还表征了 15 个品种的毛状体的密度和长度。结果表明，植物的上三分之一是最有吸引力的，成虫和定殖若虫的数量最多。在进行的生物测定中，栽培品种 BRS 9280RR、M 8808 和 M 8644IPRO 显示成虫、卵和若虫对烟粉虱的侵染水平较低。毛状体长度和密度与成虫数量、卵数和若虫定殖程度呈负相关。讨论了大豆品种对粉虱的垂直分布和吸引力。